Tissue-CRF is a potent corticotrophin releasing factor (CRF) that may sustain prolonged pituitary-adrenal activity in time of need when the usual steroid feedback would tend to "turn-off" ACTH secretion. Tissue-CRF may also play a role in the abnormal hypersecretion of ACTH in certain clinical derangements. Studies will continue on the chemical characterization of Tissue-CRF, on its tissue source of origin and on its physiological role in pituitary ACTH secretion.